Key mechanism for calculating machines



Feb. 3, 1931. DAME 1,791,265

KEY MECHANISM FOR CALCULATING MACHINES Filed Aug. 12, 1929 2Sheets-Sheet 1 Fig.1.

BY fid/r /%Qa, y 24m? ATTORNEYS Feb. 3 1931. DAME 1,791,265

KEY MECHANISM FOR CALCULATING MACHINES Filed Aug. 12, 1929 2Sheets-Sheet 2 INVENTQR B Frederic/1 Dame WM, JM, may

ATTORNEYS Patented Feb. 3. 1931 UNITED STATES PATENT OFFICE FREDERICKDAME, OF DETROIT, MICHIGAN, ASSIGNOR TO BURROUGHS ADDING MA- CHINECOMPANY, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN KEY MECHANISMFOR'CALCULATING MACHINES Application filed August 12, 1929.

This invention relates to a key mechanism for calculating machines, andit is directed particularly to a mechanism for compelling full strokesof the keys in a keydriven calculator.

In key-driven calculators the calculating mechanism is not only indexedby depression of the amount keys, but certain parts of the mechanism areactuated distances which are .1 proportional to the value of the amountkeys with the result that errors will occur.

a second time before it has been fully restored from a prior depression.In such event the calculating mechanism has not been allowed to returnto normal and the second depression of the key will not move it throughthe proper proportional.distance-to secure an accurate registration. Ittherefore becomes necessary to insure that each key is fully restoredfrom a prior depression before a subsequent depression occurs. Variouslocking devices have been provided for insuring full depression and fullrestoration of the keys of a key driven calculator, the presentinvention being directed to an improved and simplified construction.

The general object of the invention is to provide an improved mechanismfor preventing return of a partially depressed calculator key untilafter the same has been fully depressed.

A further object is to provide an improved locking mechanism thatwillnot only compel a full depression of thekey, but will also compel fullrestoration thereof before a second depression.

Other objects are to provide an improved mechanism of this characterthat is simple and inexpensive, while at the same time efficient anddurable.

Further objects and advantages of the m- Serial No. 385,271.

vention will appear from the following specification.

An embodiment of the invention is shown in the accompanying drawings inwhich:

Fig. 1 is a sectional side elevation of a calculator with the inventionapplied thereto;

Fig. 2 is a fragmentary sectional front elevation of one of the keys ofthe machine illustrated in Fig. 1;

Fig. 3 is a perspective view of one of the locking devices of theinvention;

Fig. 4 is a fragmentary sectional side elevation illustrating thelocking mechanism in normal position;

Fig. 5 is a view similar to Fig. 4 with the locking mechanism in theposition'it occupies when one of the keys has been partially depressed;and

Fig. 6 is a view similar to Fig. 4 showing the parts in the positionthey occupy when one ofthe keys has been partially restored after havingbeen depressed.

The invention is shown applied to a. Bur- -roughs key-driven calculator,the general features of which are well known as the machine has been onthe market for a number of years and is illustrated and described innumerous United States patents, as for example, Horton No. 1,016,501,No. 1,156.600, and 1,243,839. The invention may be fiisod with any othersuitable type of calculating machine and since the details of thecalculator are incidental to an understanding of the: invention, theconstruction of the calculator will be described only in a general way.

The machine has a plurality of banks of depressible amount keys numberedfrom 1 to 9 inclusive in the order of their value. These keys have keystems 10 that are provided with lateral projections 11 (Fig. 2) which,when the keys are depressed, contact a movable bar 12, the keys beingurged upward by springs 13; The rear end of bar 12 ispivoteiil at 1 1 toa triangular member 15 that swings about a pivot 16, the member 15 beingurged clockwise by a spring 17. The forward end of the bar 12 is pivotedat 18 to-a link 19 having a pin and slot pivotal connection with anindexing bar 20. The indexing bar 20 is provided with indexing stops 21adapted to obvious that if the result that an error will occur.

engage the key stems and the bar is pivoted at its rearend to thetriangular member 15. The indexing bar is pivoted at its forward end at22 to a toothed sector 23 pivoted at 24 and provided with teeth adaptedto mesh with a pinion 25 that, in turn, rotates an indicating dial 26through a one way pawl and ratchet connection with pinion 25".

When one of the amount keys is depressed, as for example the 5 key, theprojection 11 on the key stem swings the bar 12 downward and moves theindexing bar 20 forward; the latter being limited to five steps ofmovement by the engagement of one of its projections 21 with the 5 keystem. During the forward movement of the indexing bar the clockwisemovement of the pinion 25 is an idle one because of the pawl and ratchetconnection between it and the pinion 25*, but upon the return movementof the indexing bar under the influence of spring 17 the pawl andratchet connection causes pinion 25 to advance the'indicating dial 26five steps, that'is, the same number of ste s as the value of the keydepressed. It will he 5 key is not fully depressed the indexin bar willnot be moved forward to its full position with the result that, when itis returned under the influence of the spring 17 the dial 26 will not bemoved five steps. Likewise, if the 5 key is depressed a second timebefore it is fully restored, the indexing bar will not have moved backto'its fully restored position to move the dial 26 five steps before thebar will have been moved forward again, with-the It is to prevent theseerrors that the present invention has been devised.

In order to prevent the depression of more than one key of a given bankat a time, pendants 27 are provided betweenthe keys, thependants beingpivoted on shafts 28. The lower ends of the pendants are wide and thewide portions of adjacent pendants are adapted to contact one anotherunder projec tions 29 (Fig. 2) on the key stems. The entire series ofpendants for any one key bank is mounted so that thereisroom for onlyone projection 29 at a time, that is, when one key is depressed anditsprojection 29lpasses between the adjacent pendants, all the otherpendants are in contact with one another so that no other key in thatbank can *be 'depressed owing to the factthat its projection 29 cannotpass down between the pendants. As long as one key is partly or fullydepressed none of the other keys of its bank can be depressed. Thisconstruction is known and is described in Horton, No. 1,243,839.

The present invention comprehends an individual locking mechanism foreach pair of keys instead of a general locking mechanism for all thekeys. Inasmuch as the locking device for each pair of keys is the same,only one will be described, it being understood that the locking devicesfor the other pairs are the same.

Referring to Figs. 2 and 4, it will be observed that the adjacent facesof a pair of key stems 10 (the 4 and the 5 keys) are serrated at 30, theserrations being relatively small and quite numerous. Notches areprovided on the faces of the keys at both the top and the bottom of theseries of serrations, there being a set of top notches 31 andcorresponding bottom notches 32. Mounted between the key stems on theshaft 28 that carries the pendants is a yoke 33, best illustrated inFig. 3. This yoke carries a flat spring 34 which is relatively broadwhere it is attached to the yoke and gradually narrowed toward its endsso that the ends will flex more easily than the body. This spring is ofsuch length that it normallyoccupies the position illustrated in Fig. 4where its ends project into the respective lower notches 32 in the facesof the key'stems. The spring is slightly shorter than the distancebetween the bottoms of the notches, but it is longer than the distancebetween the bottom of one notch and the bottom of the serrations on theopposite key stem.

WVhen one of the keys ofthe pair is depressed, as for example the 4 key,the spring 34 moves endwise slightly until its end engages the bottom ofthe notch 32 in the 5 key stem after which the opposite end of thespring is flexed downwardly as illustrated in Fig.5. This is caused bythe serrations in the stem ofthe 4 key passing over the end of thespring and camming it downwardly. As the 4 key starts to move the firstserration swings the spring to the'right causing its opposite end toengage the bottom of the notch in the key stem of the 5 key. Themovement of the spring to the right being limited, the depression of thekey causes the spring to flex and it snaps over the serration, theposition 'of the spring during this movement being illustrated in Fig.5. If the 4 key should be released while it is only partially depressed,it will be blocked against return because, as it starts to return, oneof the serrations engages the end of the spring which tends to move thespring upwardly, but such upward movement is prevented owing to the factthat the spring cannot swing to llo the right and it is bent to aposition such that ,it cannot pass upward acrois center owing to thefact that the spring is longer than the distance between the bottom ofthe notch in the 5 key stem and the bottom of the serrations in the 4key stem. -The 4 key is thus locked against returning until it is fullvdepressed. When it is fully depressed, the end of the spring 34 movesinto the upper notch 31 of the 4 key stem.- This allows the spring tostraighten out and when the stem of the 4 key returns upward underv theinfluence of its spring the locking spring 34 is flexed in the oppositedirection as illustrated in Fig. 6. This permits the key to restorefreely but, should. an attempt be made to depress it, before it is fullyrestored, one of the serrations engages the endof the spring 34 toprevent such depression, the action being the same as in the case of apartially depressed key.

locking device acts for both keys ofits pairand the two keys cooperatein making the locking device efl'ective.

,While the locking device has been shown .for a-pair of keys, it couldbe used for only one key as is illustrated, for example, at the lefthand end of Fig. 1, where, on account of the fact that an odd number ofkeys is present in the column, it is necessary to have a locking devicefor a single key. In this case no serrations are provided on the 2 key,the face of the 2 key merely acting to prevent movement of. the lockingspring 34 to the right. Of course, if desired, any other suitable membercould be used for preventing movement of the locking spring to theright,

i it merely being necessary to prevent movement of the locking springso-that it will act on the serrations as illustrated in Figs. 5 and 6. I

It is to be understood that the construction shown is for purposes ofillustration only and that variations may be made in it withoutdeparting from the spirit and scope of the invention as defined by theappended claims.

I claim: I I 1. In combination. in a calculating machine, a depressiblekey having a key stem provided with serrations, a flexible member heldagainst endwise movement, the end of said member being adapted to passover said serrations as the key is moved, said member being mounted sothat as the key is depressed said member is flexed in one direction andas the key is restored said member is flexed in the opposite directionwhereby return of a partially depressed key and depression of apartially restored key are prevented.

2. In a calculating machine, a depressible key having a keystem providedwith serrations, a notch at each end of the series of serration, a flatspring mounted so that its end normally extendsinto one ofsaid notches,and means for preventing endwise movement of the spring.

3. In a calculating machine, a key having a key stem provided with aseries of serrations, a notch at each end of the series of serrations, apivoted arm carrying a flat spring having its end normally positioned inone of said notches, and means for limiting the movement of said arm.

4. In a calculating-machine, a pair of depressible keys, serratedmembers movable with said keys, a flat, endwise, movable flexible springmounted between said serrated members and held against endwise movementby one of said members while the other is moved, the end of said springbeing flexed in one direction by the serrations of one of said keys whenthe latter is depressed and flexed in the opposite direction as said keyis ,restored after a full depression.

5. In a calculating machine, a pair of depressible keys, serratedmembers movable with said keys, a notch in each member at each end ofthe series of serrations, and a flat, endwise movable flexible springhaving its ends normally positioned in opposing notches in said members,said spring being slightly shorter thanthe distance between the bottomsof opposing notches but longer than the distance between the bottom ofone notch and the bottom of the opposing serrations.

' 6. In combination, in a calculating ma chine, apair of depressiblekeys, serrated members movable with said keys,'said members havingnotches at each end of the series -of serrations, a pivoted membercarrying a flat spring having its ends normally positioned in opposingnotches in said serrated members, said spring being of such length thatas one of the keys is moved the spring is swung to cause one of its endsto engage the bottom of the notch in the serrated mem ber of the unmovedkey, the other end of said spring being flexed in the direction ofmovement of the moved key by the serrations moved by said key for thepurpose described.

7L In a calculating machine, a pair of de pressible keys having keystems provided with serrations, notches at the upper and at the lowerends of the series of serrations in each key stem,a pivoted yoke betweensaid key stems, and a flat spring carried by said yoke, the ends of saidspring normally occupying the opposed lower notches in said key stems,

said spring being slightly shorter than the distance between the bottomsof opposing notches but longer than the distance between the bottom ofone notch and the bottom of op osed serrations.

n testimony whereof, I have subscribed

